n. [Gr. haima, blood; koilos, hollow]1. (ARTHROPODA)The main body cavity, the embryonic development of which differs from that of a true coelom, but which includes a vestige of that true coelom that emanates from the blood spaces of the embryo, or remnants of the blastocoel after invasion of the latter by the mesoderm.2. (MOLLUSCA)The main body cavity.
Online Dictionary of Invertebrate Zoology. A.R. Maggenti and S.L. Gardne. 2005.